Hollow contact pin with wire wrap terminal and method of making same

ABSTRACT

There is disclosed a hollow contact pin comprising a tubular section which is open at one end to receive one or more wires and having extending from its closed end and integral therewith a solid elongate conductor polyhedron in cross-section forming a wire wrap terminal. The tubular part may have an inwardly extending finger to grip any wire placed therein. The method disclosed herein includes the steps of drawing a flat strip of wire into tubular form, then swaging the tube to a diameter determined for the socket portion, at the same time swaging a further advanced portion of the tube to reduce the diameter to form a solid circular rod, at the same time at an advanced portion of the workpiece swaging the circular portion to form a wire wrap terminal which is substantially square in crosssection, and at the same time piercing the forward end of the most advanced tubular socket portion to open and flare the same, and finally separating the completed socket pin-wire wrap terminal from that following it. If the socket portion is to be provided with a wire-engaging finger, the flat strip is first lanced at determinate distances before being drawn into tubular form.

United States Patent [1 1 Barnes et al.

[ July 24, 1973 HOLLOW CONTACT PIN WITII WIRE WRAP TERMINAL AND METHOD OF MAKING SAME [75] Inventors: Robert E. Barnes, Trumbull; Nelson A. Secor, Danbury, both of Conn.

[73] Assignee: The Bead Chain Manufacturing Company, Bridgeport, Conn.

[22] Filed: Sept. 9, 1971 [21] Appl. No.: 179,074

Primary Examiner-Joseph H. McGlynn Attorney-Johnson & Kline [57] ABSTRACT There is disclosed a hollow contact pin comprising a tubular section which is open at one end to receive one or more wires and having extending from its closed end and integral therewith a solid elongate conductor polyhedron in cross-section forming a wire wrap terminal. The tubular part may have an inwardly extending finger to grip any wire placed therein. The method disclosed herein includes the steps of drawing a flat strip of wire into tubular form, then swaging the tube to a diameter determined for the socket portion, at the same time swaging a further advanced portion of the tube to reduce the diameter to form a solid circular rod, at the same time at an advanced portion of the workpiece swaging the circular portion to form a wire wrap terminal which is substantially square in cross-section, and at the same time piercing the forward end of the most advanced tubular socket portion to open and flare the same, and finally separating the completed socket pinwire wrap terminal from that following it. If the socket portion is to be provided with a wire-engaging finger, the flat strip is first lanced at determinate distances before being drawn into tubular form.

1 Claim, 10 Drawing Figures HOLLOW CONTACT PIN WITH WIRE WRAP TERMINAL AND METHOD OF MAKING SAME This invention relates to hollow contact pins having at one end a wire wrap terminal.

Heretofore such pins consisted of two separate pieces, viz., a tubular socket open at one end and a length of wire which was soldered or otherwise secured to the bottom end of the tubular socket. The separate parts of such hollow contact pins have been difficult to make, handle and assemble, being over all in the order of 1.25 inch long with the socket portion about 0.260 inch long and having a diameter of about 0.045 inch and the wire wrap terminal portion being about l.000 inch long and 0.025 inch in diameter.

An object of this invention is to provide a hollow contact pin and wire wrap terminal as an integral swaged piece thereby obviating the need for separately making and handling the socket and wire terminal portions.

A feature of this invention is the provision of a method whereby the socket and terminal portions may be made in a swaging machine in a continuous method from a flat strip of metal of indefinite length and determinate width, in which the hollow contact pin and wire wrap terminal unit may be delivered from the swaging machine in finished form ready for packaging and shipment.

Briefly, the objects of this invention have been achieved by advancing a continuous strip of flat metal from station to station to progressively form to desired shape and size a hollow contact pin with an integral wire wrap terminal. At the first station the continuous strip is preferably lanced at spaced intervals while in flat condition to provide wire-retaining fingers.

While the lanced strip is being advanced toward the next station, the strip is drawn through drawing dies to form a tube with the fingers, if present, extending into the tube. At the next station, simultaneously with the lancing operation, the tube is progressively swaged to form opposite ends of an adjacent socket portion an intermediate portion which is first reduced in diameter to produce a solid rod and then further swaged to produce a wire wrap terminal having a polyhedron in crosssection. At a final station the end of the furthest advanced wire terminal is severed from the adjacent end of the socket portion and at the same time a punch is applied to the leading end of the terminal socket section to open the end of the socket and expand it to provide a flaring wire-receiving mouth.

These are simple operations, which are relatively inexpensive to tool. Since the operations are simple and are performed simultaneously on longitudinally spaced portions of the metal strip, and require no assembly operation, it is possible according to the present invention to increase the rate of production and reduce the cost of manufacturing hollow contact pins with wire wrap terminals.

Other features and advantages will hereinafter appear.

in the accompanying drawings:

FIG. 1 shows the hollow contact pin with an integral wire wrap terminal of the present invention.

FIG. 2 is an enlarged view, partly in section, of the contact pin of FIG. 1.

FIG. 3 is an end elevation of the contact pin.

FIG. 4 is a plan view of a flat strip of metal showing a first portion which has been lanced at spaced intervals to ultimately form the wire-retaining fingers.

FIG. 5 shows a portion of the continuous strip which contains the lanced portions being drawn into tubular form.

FIG. 6 shows the tube after it has been progressively constricted between the socket sections to form a solid portion circular in cross-section.

FIG. 7 shows the solid portion between adjacent socket sections swaged into a square cross-section.

FIG. 8 shows the cut-off and swaging station of the finished contact pin.

FIG. 9 is a transverse section taken on the line 9-9 of FIG. 6 of the solid cylindrical portion of the wire wrap and part of the dies forming it.

FIG. 10 is a transverse section taken on the line l0l0 of FIG. 7 of the solid square portion of the wire wrap.

As shown in FIG. 1, the article of the present invention is a hollow contact pin 10 having a closed end 11 and a socket portion 12 provided with an expanded opening or mouth 13 at the other end to receive the bare end of a wire conductor 14, see FIG. 2, to make electrical contact therewith. To insure good contact and prevent the wire 14 from being inadvertently pulled from or falling out of the socket portion 12, the latter is provided with an inwardly projecting resilient finger 15 whose free end is directed toward the closed end 11 of the socket. Due to the resiliency of the metal, the finger 15 firmly forces the wire 14 against the opposite sides of the socket portion 12 and yielding resists withdrawal of the wire therefrom. The socket portion 12 may have an outside diameter permitting it to slidably fit in one of a plurality of holes in a suitable receptacle or board, along with many like contact pins.

Such contact pins have heretofore been provided with terminals about which bare wire may be wrapped to make contact with the socket portion and any wire or wires therein. Such wire wrap terminals have heretofore been made as separate pieces which were soldered, or otherwise secured, to the separately made socket portions.

The work of making the sockets and wire terminals separately and securing them together is a difficult and costly operation, especially because the parts are very small and difficult to handle, the socket portion being in the order of 0.045 inch in diameter and 0.260 inch in length, while the wire wrap terminal is about 0.025 inch in diameter and 1.000 inch long. Moreover the socket portion and the terminal are subject to becoming loose and separate and thus fail to provide good electrical connections.

According to the present invention, the contact pin socket l2 and wire wrap terminal 16 are integral, being made from a strip 17 of flat metal in a continuous method and are delivered in finished form without intermediate handling by the operator.

As indicated in the accompanying drawings, in practicing the method of this invention in its presently preferred form, the flat metal strip 17 of indefinite length is, as shown in FIG. 4, lanced at pin-length intervals as the strip is advanced step-by-step to a suitable lancing tool to thus provide a succession of the fingers 15 which are caused to extend away from the body of the strip. The lanced strip 17, as it continues to advance, is rolled by drawing die 18 into a tube 19, shown in FIG. 5, bringing the longitudinal edges of the strip 17 together and in contact with each other. In the drawing operation of the strip 17, due to the fact that the fingers are flat and extend freely from the strip, they advantageously extend somewhat further into the tube 19.

After the tube has been formed (see FIG. 5), it is advanced to position, shown in FIG. 6, between swaging dies 20. These dies are so shaped that they form a constricted portion 21 in the tube 19, and spaced forwardly from the portion 21, another constricted portion 22. Between the portions 21 and 22 the tube 19 is swaged by the dies 20 to form a solid cylindrical portion 23. At the next station, the portion 23 is further swaged so as to form the wire wrap portion 16 which In swaging the wire wrap terminal having the square or other polyhedral cross-section, the terminal 16 is provided with sharp edges at the corners 24 to bite into and make good electrical contact with wires to be wrapped about the terminal section. Instead of being swaged to square cross-section form, the terminal may be swaged to a triangular form within the scope of the invention.

Variations and modifications may be made within the scope of the claims and portions of the improvements may be used without others.

We claim:

1. A hollow contact pin comprising an elongate wirereceiving socket portion having a flared open end and a closed end and having integral with its closed end an elongate square solid wire wrap terminal, said socket having an integral resilient finger extending inwardly from adjacent said open end toward said closed end to be engaged by and frictionally hold a wire conductor inserted in said open end of the socket. 

1. A hollow contact pin comprising an elongate wire-receiving socket portion having a flared open end and a closed end and having integral with its closed end an elongate square solid wire wrap terminal, said socket having an integral resilient finger extending inwardly from adjacent said open end toward said closed end to be engaged by and frictionally hold a wire conductor inserted in said open end of the socket. 